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BTO Blueline
WREN
Troglodytes troglodytes
Wren © Tommy Holden
Conservation listings
Europe: no SPEC category (favourable conservation status in Europe, not concentrated in Europe)
UK: Green
Long-term trend
UK, England: moderate increase
Distribution maps
Maps and statistics from British and Irish
atlases can be viewed here.
Status summary
Following a rapid increase up to the mid 1970s, Wren abundance has fluctuated; BBS results suggest further recent rise in all parts of the UK, and numbers are currently close to the previous peak levels. Abundance can vary sharply from year to year in this species, influenced by mortality rates that may be very high in severe winters and by the species' high breeding potential (Peach et al. 1995b), although this is largely concealed by smoothing in the CBC/BBS trends. Clutch and brood sizes have shown some small improvements in the long term, although the percentages of juveniles at CES sites have fallen slightly.
 
CBC/BBS UK graph
 
Table of population changes for Wren
Source Period
(yrs)		 Years Plots
(n)		 Change
(%)		 Lower
limit		 Upper
limit		 Alert Comment
CBC/BBS UK 35 1967-2002 622 99 69 124    
  25 1977-2002 792 25 8 31    
  10 1992-2002 1630 20 14 23    
  5 1997-2002 2145 25 20 27    
CBC/BBS England 35 1967-2002 501 98 68 129    
  25 1977-2002 633 24 9 34    
  10 1992-2002 1285 19 12 22    
  5 1997-2002 1672 27 22 28    
CES adults 18 1984-2002 93 51 . .    
  10 1992-2002 109 12 . .    
  5 1997-2002 110 8 . .    
CES juveniles 18 1984-2002 92 44 . .    
  10 1992-2002 107 3 . .    
  5 1997-2002 108 8 . .    
BBS UK 9 1994-2003 1816 17 13 20    
BBS England 9 1994-2003 1409 10 6 13    
BBS Scotland 9 1994-2003 176 56 36 80    
BBS Wales 9 1994-2003 158 5 -5 16    
BBS N.Ireland 9 1994-2003 66 64 28 110    
BBS acknowledgement
 
CBC/BBS England graph
CES adult abundance graph
CES juvenile abundance graph
BBS UK graph
BBS England graph
BBS Scotland graph
BBS Wales graph

BBS N Ireland graph
 
Table of productivity information for Wren
Variable Period
(yrs)		 Years Mean
annual
sample		 Trend Predicted
in first year		 Predicted
in last year		 Change Comment
Clutch size 34 1968-2002 96 Linear increase 5.6 eggs 5.82 eggs 0.22 eggs  
Brood size 34 1968-2002 96 Linear increase 4.78 chicks 5.16 chicks 0.38 chicks  
Daily failure rate (eggs) 34 1968-2002 143 None        
Daily failure rate (chicks) 34 1968-2002 99 None        
Laying date 34 1968-2002 88 Linear decline day 134 day 130 -4 days  
Percentage juveniles (CES) 18 1984-2002 97 Smoothed trend 106 productivity index 102 productivity index -5%  
Percentage juveniles (CES) 10 1992-2002 112 Smoothed trend 115 productivity index 102 productivity index -13%  
Percentage juveniles (CES) 5 1997-2002 113 Smoothed trend 104 productivity index 102 productivity index -4%  
 
Clutch size graph
Brood size graph
Egg nest failure graph
Chick nest failure graph
Laying date graph
CES productivity graph
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This report should be cited as:
Baillie, S.R., Marchant, J.H., Crick, H.Q.P., Noble, D.G., Balmer, D.E., Beaven, L.P., Coombes, R.H.,
Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. and Thewlis, R.M. (2005)
Breeding Birds in the Wider Countryside: their conservation status 2004.
BTO Research Report No. 385. BTO, Thetford. (http://www.bto.org/birdtrends)

Pages maintained by Susan Waghorn and Iain Downie: Last updated 18 January, 2006